Rationalize arg handling for pub build and serve.

sdk/lib/_internal/pub/test/barback/subdirectories_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:path/path.dart' as p;
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../descriptor.dart' as d;
+import '../serve/utils.dart';
+import '../test_pub.dart';
+
+main() {
+  initConfig();
+
+  setUp(() {
+    d.dir(appPath, [
+      d.appPubspec(),
+      d.dir("web", [
+        d.dir("one", [
+          d.dir("inner", [d.file("file.txt", "one")])
+        ]),
+        d.dir("two", [
+          d.dir("inner", [d.file("file.txt", "two")])
+        ]),
+        d.dir("nope", [
+          d.dir("inner", [d.file("file.txt", "nope")])
+        ])
+      ])
+    ]).create();
+  });
+
+  var webOne = p.join("web", "one");
+  var webTwoInner = p.join("web", "two", "inner");
+
+  integration("builds subdirectories", () {
+    schedulePub(args: ["build", webOne, webTwoInner],
+        output: new RegExp(r'Built 2 files to "build".'));
+
+    d.dir(appPath, [
+      d.dir("build", [
+        d.dir("web", [
+          d.dir("one", [
+            d.dir("inner", [d.file("file.txt", "one")])
+          ]),
+          d.dir("two", [
+            d.dir("inner", [d.file("file.txt", "two")])
+          ]),
+          d.nothing("nope")
+        ])
+      ])
+    ]).validate();
+  });
+
+  integration("serves subdirectories", () {
+    pubServe(args: [webOne, webTwoInner]);
+
+    requestShouldSucceed("inner/file.txt", "one", root: webOne);
+    requestShouldSucceed("file.txt", "two", root: webTwoInner);
+    expectNotServed("web");
+    expectNotServed(p.join("web", "three"));
+
+    endPubServe();
+  });
+}